Sketch has a bad glitch

Something’s not working the way it seems like it should.

When I draw on a sketch

I saw some of the lines flashing or my work covered up by blue/green radial lines.

This happened on Friday on several different activities. Refreshing the screen does not fix it. It happened to both me and my students.

Is there any way to fix this or prevent it?

Here is a screenshot:

We’ve seen something similar when users have GPU / GPU driver / Browser compatibility issues, or when a browser extension causes trouble. Can you try the affected activities out from an incognito window?

If the problem goes away. try turning off your browser extensions one at a time until you find the one causing you trouble.

If it doesn’t, can you send an email to We’re better equipped to handle this sort of thing there.

Of course it’s working fine now… I will try the extensions thing next time the glitch pops up. Thanks!